[flang] Avoid deallocation of intent(out) when dummy arg is not in entry stmt

In some case, the ENTRY statement in a procedure is including some
dummy argument. Until now, deallocation of intent(out) allocatable was
not checking for this and it could result in a segmentation fault.

This patch avoids deallocation when the value is not in the ENTRY stmt.

Reviewed By: jeanPerier, PeteSteinfeld

Differential Revision: https://reviews.llvm.org/D134342